Bell Work This graph represents 2 falling objects

Bell Work This graph represents 2 falling objects. 1) ___ (A, B) is moving faster because ________. 2) ___ is experiencing more air resistance since ______. 3) Draw a Velocity-Time graph of the same situation. B y (m) v (m/s) A t (s) Which has a larger acceleration on the moon: feather or hammer?

• Free Fall- (according to Webster's dictionary) 1. “Thefallofofaabodysuchthatthe theonlyforceacting upon itupon is that gravity”. acting it isofthat of gravity”Assume no air resistance! 2. “The part of a parachute jump that precedes the opening of the parachute” Reread def. #1 - this is the physics definition we will be using; “only force” means no air resistance.

What letter do YOU think best answers the following question? An Object that is “free fallin’” will tend to… • A. fall at a constant velocity • B. Get faster and faster until the moment it hits the ground • C. Get faster to a certain point, then level off • D. It depends on the mass and shape of the object • D. Remember, always assume no air resistance during THIS unit

Let’s look at two situations • Dropping something from rest • Throwing an object upward

Time velocity displacement (Δy) 1 sec. -9. 80 m/s 4. 9 m Increase 9. 80 m/s 2 sec. -19. 6 m/s 19. 6 m Increase 9. 80 m/s 3 sec. -29. 4 m/s 44. 1 m Increase 9. 80 m/s 4 sec. -39. 3 m/s Increase continues 78. 4 m Think of it as 9. 80 m/s per second

Free Fall Facts 1. Gravity makes all objects accelerate downward constantly no matter what direction they are presently moving. 2. The velocity at the top of a trajectory (path) for an object that is thrown straight upwards = 0 m/s. 3. Acceleration due to gravity on Earth is a constant, g. 4. While g is 9. 81 m/s 2 down, we will use 10 m/s 2 for simplicity. 10 m/s 2 down In reality this constant varies between 9. 79 and 9. 81 depending on where you are in the world.

A) -9. 8 m/s 2 B) 0 C) Neither of these!

What would happen if gravity were “turned off” at the exact moment the ball reached the tippity-top of its flight? A) The Ball would hover B) Keep going up C) Go down

The trajectory has symmetry A motion diagram illustrates this:

Gravity problems • No new formulas needed! Just use Δy instead of Δx. • Remember that gravity causes an acceleration of a = -10 m/s 2

Free Fall problem #1 If a penny is dropped from the Empire State building (height h = 373 m, Δy= -373 m) a) how long does it take to hit the ground? b) how fast is it going?

Free Fall Problem #2 A certain cell phone app encourages you to toss your phone up in the air, and it will determine how high you threw it. If you are risk averse, you can calculate how high a phone would go if it were in the air for, say, 1. 8 seconds. Calculate the vertical displacement, Δy. (Hint: at the top of the path, the phone is not moving up or down. )

Free Fall Problem #3 A certain cell phone app encourages you to toss your phone up in the air, and it will determine how high you threw it. If you are risk averse, you can calculate how high a phone would go if it were in the air for, say, 1. 8 seconds. Now calculate: - velocity at which it was thrown - velocity it lands in your hand - velocity after 0. 5 s.

Free Fall Problem #2 A farmer drops a watermelon from the top of a barn. It takes 1. 00 second to hit the ground. a) How high is the barn? • What are you solving for? Which kinematic is useful? • Can you solve this without a calculator? b) How FAST is it going at 1. 00 second?

Free Fall Problem #3 A giant rubber band ball (2, 524 lbs) drops from a plane 1828. 2 m above the ground. Ignore the horizontal velocity of the plane. a) How fast will it be going as it hits the ground in m/s? b) Convert this answer to miles per hour. c) How long will it take to reach the ground? Free Fall Problem #4 A person throws a smart phone straight up into the air. It takes 1. 50 seconds to be caught at the same height from which it was thrown. How high did it go?

p. 64 1 a. -42 m/s b. 11 s 2 a. 22. 1 m/s b. 2. 25 s 3 a. 8. 0 m/s (speed) -8 m/s (velocity) b. 1. 63 s p. 65 3. At max height v = 0; a = -9. 8 m/s 2; just before ball hits the ground a = -9. 8 m/s 2 5. we’ll discuss 32. 0. 60 s 48. 310 m; 8. 5 s; 16. 4 s

• Ex 3. A first-aid kit is dropped by a rock climber who is descending steadily at 1. 3 m/s After 2. 5 s, what is the velocity of the first-aid kit, and how far is it below the climber?

CNN. com article • Man drops world's biggest rubber band ball out of a plane. A Welshman spent five years creating the world's biggest rubber band ball - then dropped it out of a plane to see if it would bounce. • Tony Evans, 54, from Swansea, dropped the one-tonne record-breaking ball from a mile up over Arizona. • It took 20 seconds to hit the ground and created a 4 ft wide crater and a 20 ft cloud of dust - but did not bounce. • The ball collapsed on impact and the remains stayed firmly in the bottom of the crater, reports the Daily Record. • Mr Evans, who earned a place in the Guinness Book of Records with his ball, said: "It was my pride and joy. • "People were always asking me what would happened if the ball was dropped from a great height. Would it bounce or explode? No one knew. • "I'd have loved to see it bounce up into the sky. But it was an incredible sight. " • A TV show paid for the ball to be dropped out of a plane above the Mojave Desert and a skydiving cameraman filmed its descent.

Challenge Question • A gibbon monkey throws a small (rolled-up) armadillo into the air. It takes 6. 00 second to come back down and be caught (from the same point it was thrown). How high did it go?

Other Physics that day… • KINGMAN, Arizona (CNN) -- A TV crew for the show "Ripley's Believe It Or Not!" crashed in the Arizona desert while trying to film the bounce of the world's largest rubber band ball, officials said Monday. • None of the three people on board the A-Star helicopter was seriously hurt in the Sunday crash, said Jarrod Lyman, spokesman for the Mohave County Sheriff's Department. They included the pilot and two crew members. • Deputies believe the chopper was flying low to film a convoy heading out to the bounce site when it clipped power lines along U. S. Highway 66, 10 miles east of Kingman, Lyman said. • "The pilot just did not see the wires, " he said. Lyman described weather at the time as "windy but decent. " • The pilot was not hurt, he said. The two others were taken to Kingman Regional Medical Center and received treatment for minor injuries. • The National Transportation and Safety Board and the FAA were notified, Lyman said, and the incident was under investigation. • Lyman said he did not know whether the rubber band ball bounce went off as scheduled. A spokeswoman for Sony Pictures could not be reached for comment. CNN-com

Bell work: Date: On a far off planet, [you drop a ball and it falls 40. 0 meters in 4. 5 seconds. What is the acceleration due to gravity on this planet]? Is this planet larger or smaller. Smaller (less massive) than earth? a= -4. 0 m/s 2

• American test for giant rubber ball • The rubber ball will have a test bounce in the USA • The world's biggest rubber ball constructed by a man from Swansea is to be flown all the way to America for its first bounce. An American TV show is going to drop Tony Evans' huge rubber ball to see if will actually bounce back from the ground. • • • • • I'm not sure if it will bounce or just go 'boing' and fall apart Tony Evans The American TV Show Ripley's Believe It Or Not, which features all things weird and wacky, is flying the 62 -year-old from Portmead in Swansea out to the US next month. The ball, which contains more than six million rubber bands and weighs 2, 524 lbs, will then be tested a location in the States and the results filmed. However, Mr Evans, a full-time foster carer, is uncertain whether the ball will survive the experiment. "I'm not sure if it will bounce or just go 'boing' and fall apart. "But it will be a fitting end for it to be dropped from the sky. The Millennium Stadium hosts the weigh-in "I'll be glad to see the back of it. It's not a very practical thing to have around the house. " For the last five years, building the ball - with rubber bands donated from across the UK - has been a painstaking labour of love for Mr Evans. It has steadily grown in size and in May a weigh-in at Cardiff's Millennium Stadium certified the giant object as a Guinness World Records winner. The ball weighed in at 2, 524 lbs, squashing the previous figure of 2, 450 lbs. The impressive object now has a circumference measuring 14 ft 8 ins, a diameter of 4 ft 6 ins and stands 4 ft 5 ins tall. Despite its massive size - dwarfing rivals made by other rubber band enthusiasts- the ball serves a purpose. Mr Evans takes it to events around the UK to raise money for charity.